Quick attachment structure for drill shank

ABSTRACT

A shank fitting structure simple in structure and easy to machine and assemble. A shank ( 20 ) has an external diameter large enough to allow it passage in a state where a detent member ( 5 ) is moved bach radially outward, and includes a stepped portion ( 21 ) for butting by providing a small diameter portion on the end side an d a recess ( 23 ) for housing the projecting part of the detent member ( 5 ) formed in the tip part. On the internal circumferential face of an opening part ( 2 ) of an arbor A, a first sleeve ( 6 ) is provided and pressed by an elastic member ( 8 ) toward the edge of the opening in such a way that its tip comes into contact with the stepped portion ( 21 ) of the shank ( 20 ) and its external circumferential face can keep the detent member ( 6 ) back toward the external circumference. A holding hole ( 9 ) for holding the detent member ( 5 ) within the range of its sliding movement is made in the wall of the arbor A, and a second sleeve ( 3 ) capable of being moved back toward the base end and pressing the detent member radially inward by the inner circumferential face when the second member is moved back toward the base end is disposed on the external circumferential face of the arbor.

This application claims the benefit of Provisional Application No.60/039,563 filed Feb. 8, 1997.

TECHNICAL FIELD

The present invention relates to a shank attaching structure in which ashank can be attached and detached to and from an arbor on a drillingmachine side with one touch, that is, quickly and easily.

TECHNICAL BACKGROUND

Conventionally, there has been a shank attaching structure capable ofattaching and detaching, with one touch, a shank of a cutter to and froman arbor having a base end portion fixed to a drilling machine (aelectric hand drill or a drilling machine). In the one-touch type shankattaching structure, the shank of the cutter can be attached to thearbor with one touch by means of an engagement mechanism providedbetween the arbor and the shank by only inserting the shank of thecutter upward into an opening portion formed on a lower face of thearbor.

In the one-touch type shank attaching structure, however, a ring-shapedmember (sleeve) provided on the outer periphery of the arbor should berelatively rotated with respect to an arbor body when the shank is to bedetached from the arbor. With such a structure, for example, there is adisadvantage that the shank drops down if something comes in contactwith the ring by mistake during the rotation of the drilling machine. Insuch a structure, furthermore, it is necessary to grip the shank by oneof hands and to grip and rotate a ring-shaped member provided on theouter periphery of the arbor by the other hand, thereby relativelyrotating the ring-shaped member with respect to the arbor body in anordinary detaching work. More specifically, when the work of detachingthe shank is to be performed, both hands should always be usedinevitably.

With the shank attaching structure, furthermore, a concave portion foraccommodating a part of a ball acting as an engagement member to beprojectable into the inside diameter side should be provided on theinner peripheral face of the ring-shaped member. The depth of theconcave portion becomes deeper in one rotational direction (almostU-shaped as seen in a section), that is, the internal face of thering-shaped member (sleeve) is processed and the depth of the concaveportion is gradually changed. Therefore, a special machine tool isrequired and a machine work is difficult to perform. As a result, amanufacturing cost is increased. In the shank attaching structure,furthermore, a plurality of coiled springs with small diameters shouldbe provided for springs to energize the ring-shaped members in thedirection of the rotation on the internal face of the ring-shaped memberagainst the direction of the rotation. Accordingly, an inclined hole forholding the spring should be formed on the inner peripheral face of thering-shaped member and the outer peripheral face of the arbor body, andassembly should be performed with the spring held in that state. As aresult, a very difficult work should be inevitably carried out. Inparticular, it takes plenty of time and requires labors for processingto form the inclined hole with a predetermined angle on the innerperipheral face of the ring-shaped member. Furthermore, theabove-mentioned one-touch type shank attaching structure is complicated.Therefore, a coolant cannot be supplied from the inside to a cuttingedge portion of the tip of the shank. Accordingly, the coolant should besupplied from the outer periphery of the tool. For this reason, thecoolant should be scattered to perform a drilling work. As a result,there has been a drawback that the coolant contaminates thecircumference of a portion to be drilled and is scattered over anoperator.

The present invention has been made in consideration of thecircumstances, and it is an object of the present invention to provide ashank attaching structure which eliminates the above-mentioneddrawbacks.

DISCLOSURE OF THE INVENTION

In order to solve the above-mentioned problems of the art, a firstaspect of the present invention is directed to a shank attachingstructure in which an engagement member is provided on an innerperipheral face of an opening portion formed on a tip of an arbor so asto freely retreat in a direction of an outside diameter, and a shankprovided on a base end of a cutter is detachably attached to the openingportion of the arbor with one touch,

wherein the shank is formed to have such an outside diameter as to passin a state in which the engagement member provided on the arbor retreatsin the direction of the outside diameter, a diameter of a base endportion of the shank is further reduced to form a stepped portion forabutment, and a concave portion(s) for accommodating a projected portionof the engagement member projected in a direction of an inside diameteris /are formed on a tip side portion of the stepped portion,

a first sleeve is provided on the inner peripheral face of the openingportion of the arbor in such a manner that a tip of the first sleeve canabut against the stepped portion of the shank to retreat toward a baseend side and the state in which the engagement member is caused toretreat in the direction of the outside diameter can be kept by an outerperipheral face of the first sleeve,

a holding hole for holding the engagement member in a slide operationregion of the first sleeve is formed in a wall portion of the arbor,

the state in which the engagement member retreats in the direction ofthe outside diameter is kept until a tip of the first sleeve pressedtoward an open end by an elastic member to be abut by the steppedportion of the shank,

a second sleeve is provided on the outer peripheral face of the arborfor being moved in at least one of directions of an axial tip and a baseend, pressing the engagement member in the direction of the insidediameter by the inner peripheral face of the second sleeve with themovement in one of the directions, and accommodating the engagementmember in the direction of the outside diameter without the movement inone of the directions, and

the second sleeve is pressed in one of the directions by an elasticmember, thereby keeping a state in which the engagement member isaccommodated in the concave portion of the shank, and the second sleeveis moved in a direction opposite to the one of the directions againstelastic force of the elastic member, thereby causing the engagementmember to retreat in the direction of the outside diameter.

According to the shank attaching structure in accordance with thepresent invention, when the second sleeve is simply caused to slide inone of the axial directions (the direction of the base end side or tipside) against the elastic member, the press of the engagement member inthe direction of the inside diameter is released so that the engagementmember retreats (moves) toward the outside diameter in the radialdirection. As a result, the engagement of the shank by the engagementmember is released. Consequently, the shank of the cutter can easily bedetached from the arbor. Furthermore, when attaching the shank to thearbor, the shank is simply inserted into the opening portion of thearbor. Consequently, the stepped portion for abutment of the shankcauses the first sleeve to retreat toward the base end side of thearbor. As a result, the engagement member projects toward the insidediameter in the radial direction. By the inserting operation, theengagement member is moved over the outer peripheral face of the shankin the axial direction in contact therewith. As a result, a projectedportion of the engagement member toward the inside diameter side isaccommodated in the concave portion formed in the shank. Thus, the shankis held in the arbor.

Accordingly, an operator can simply insert the shank into the openingportion of the arbor when attaching the shank, and can easily detach theshank by causing the second sleeve to slide toward the tip or the baseend side against the elastic member. In other words, the shank caneasily be attached and detached to and from the arbor by one hand.Furthermore, the second sleeve slides in one of the directions (thedirection of the tip side or base end side) so that the shank can beattached and detached. Therefore, even if something abuts against thesecond sleeve by mistake in the direction of rotation as in aconventional manner, the shank never drops off. In the structure inwhich the engagement of the engagement member is released by pressingthe second sleeve toward the base end side and causing the second sleeveto slide toward the tip side, particularly, even if the second sleeveabuts against a foreign substance or a projection on the side of anobject to be drilled, the engagement state of the shank is not affected.Therefore, such a structure is excellent in workability.

In respect of works, the shank attaching structure according to thepresent invention can be obtained by circular works or a combinationthereof. Therefore, the structure is easy to work and can easily beassembled.

In the shank attaching structure, if the engagement member is aball(globe), the elastic member for pressing the first sleeve is formedof a coiled spring having such a dimension as to cause the outerperiphery of the coiled spring to be provided along the inner peripheralface of the opening portion of the arbor, and the elastic member forpressing the second sleeve is a coiled spring having such a dimension asto cause the inner periphery of the coiled spring to be provided alongthe outer peripheral face of the arbor and to cause the outer peripheryof the coiled spring to be provided along the inner peripheral face ofthe second sleeve, and the shank attaching structure can particularly beformed simply and becomes easy to work and assemble.

Furthermore, in the shank attaching structure wherein the openingportion of the arbor is extended toward the base end side to form a holeportion for supplying a coolant and to form, on the hole portion, athrough hole having a tip open and extending in a radial direction isformed on the hole portion, a ring member is rotatably attached to thearbor on the outer periphery of the arbor where the hole is positioned,and a sealing member for a liquid seal is provided between the ringmember and the arbor, and

a passage for inserting the coolant from an upper end toward a tip sideis formed in an axial core portion of the shank, it is possible toprovide a drill capable of supplying the coolant from the inside of therotating shank to a cutting edge portion also in the one-touch typeshank attaching structure.

Moreover, in the shank attaching structure, a coiled spring is providedin the hole portion for supplying the coolant, and a center pin isprovided in a inserting hole of the shank so as to retreat toward thehole portion side in such a manner that it is pressed toward a tip (ofthe center pin) side by the coil spring and the tip projects from a tipof a cutter, and

a flange portion is formed in a base end portion of the center pin forbeing engaged with the shank side when the center pin projects, and aliquid sealing mechanism is formed for performing a liquid seal in astate in which the flange portion abuts against an engagement face of anupper end of the inserting hole with which the flange portion isengaged, so that the coolant can be supplied to the cutting edge portionside only during necessary drilling. Accordingly, the structure isexcellent in that the coolant can be prevented from being consumedwastefully and the coolant is not scattered unnecessarily. In addition,the liquid sealing mechanism is constituted by the center pin and theinserting hole for supporting the same. Therefore, a very simplestructure can be obtained.

Furthermore, in the shank attaching structure, the flange portion andthe engagement face forming the liquid sealing mechanism comprisetapered faces which are contacted each other, it is possible to obtainthe liquid sealing mechanism which is simple, reliable and durable.

In the shank attaching structure, a groove for forming a coolant passageis provided below a position which is lower by a predetermined dimensionbased on a lower part of the flange portion of the center pin in thecomposition which includes the outer peripheral face of the center pinand the inner peripheral face of the inserting hole of the shank whichis in contact with the outer peripheral face, the supply of the coolantcan be started only when the center pin enters the position which islower by the predetermined dimension, that is, the cutting is startedand the coolant is required. Therefore, the coolant can be preventedfrom being consumed wastefully.

Furthermore, in the shank attaching structure in which the position thatis lower by the predetermined dimension is substantially equal to adimension with which the center pin projects from a cutting edge portionon the tip of the shank toward the tip side in a free state in which thecenter pin is pressed from the base end toward the tip by the coiledspring, the coolant is supplied only when the cutting is started.Therefore, it is possible to obtain the structure which avoids waste andis excellent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a right half portion of the wholeconstruction of a shank attaching structure according to a firstembodiment of the present invention.

FIG. 2 is a sectional view showing a right half portion of theconstruction on an arbor side with a cutter detached from the shankattaching structure illustrated in FIG. 1.

FIG. 3 is a sectional view taken along an arrow I—I in FIG. 2.

FIG. 4 is an enlarged view showing a main part of a cut right halfportion of an opening portion of an arbor illustrated in FIG. 2.

FIG. 5 is an enlarged view showing a main part of the cut right halfportion of the opening portion of the arbor with a shank of the cutterinserted therein as illustrated in FIG. 1.

FIG. 6 is a partially enlarged view showing the detailed construction ofa center pin of the cutter whose tip and right half portion areillustrated in FIG. 1 and that of a through hole portion of the cutterthrough which the center pin is inserted.

FIG. 7 is a sectional view showing a right half portion of theconstruction on the arbor side with a cutter detached from a shankattaching structure according to a second embodiment.

FIG. 8 is a sectional view showing a right half portion of the wholeconstruction of the shank attaching structure according to the secondembodiment illustrated in FIG. 7.

FIG. 9 is an enlarged view showing a main part of the shank attachingstructure illustrated in FIG. 8.

FIG. 10 is an enlarged view showing a state in which a center pin isbrought into the base end side of the arbor in the shank attachingstructure illustrated in FIG. 9.

FIG. 11 is an enlarged sectional view taken along the line II—II in FIG.10, showing a groove formed on the peripheral face of the center pin forsupplying a coolant.

BEST MODE FOR CARRYING OUT THE INVENTION

While a shank attaching structure according to an embodiment of thepresent invention will be specifically described below with reference tothe drawings, the present invention is not restricted to the presentembodiment.

First Embodiment

In FIGS. 1, 2 and 3 showing a first embodiment, A denotes an arbor and Bdenotes a cutter. The arbor A has an opening portion 2 on a tip of anarbor body 1 (a lower end in FIGS. 1 and 2) and a second sleeve 3 isslidably provided in an axial direction (a longitudinal direction : avertical direction in FIGS. 1 and 2) along an outer peripheral face 1 aof the arbor body 1 on the outer periphery of the opening portion 2 asshown in FIG. 1 or 2. In addition, the second sleeve 3 is pressed towardthe base end side of the arbor A by a coiled spring 4 in the presentembodiment.

It is possible to employ such a structure as to press the second sleeve3 toward the tip side of the arbor A on a direction basis. The coiledspring 4 is provided to have an inner periphery formed along the outerperipheral face of the arbor body 1 and an outer periphery formed alongthe inner periphery of the second sleeve 3.

The second sleeve 3 shown in FIGS. 1 and 2 is formed by three members,that is, a body 3A, a cover 3B and a cover 3C which are ring-shapedrespectively as enlarged in FIG. 4. An inner face of the body 3A isprovided with an annular groove 3 a (an annular shape formed by asubstantially round locus) having a U-shaped section for accommodating apart (an outside part) of a metallic ball(globe) 5 acting as anengagement member and a groove 3 b for engaging the coiled spring openedon a lower end. The cover 3B is made of a synthetic resin. The cover 3Bcovers an upper end of the body 3A and is integrally fixed by means ofan engagement structure 3 d including concave and convex portions formedthereon. The cover 3C is made of metal, and a lower end thereof is benttoward the body 3A side to engage a lower end of the coiled spring 4 andan upper end thereof is attached (caulked) in the body 3A and isintegrally fixed thereto with the lower end of the body 3A covered withthe upper end. On the arbor body 1 side are provided an engagement ring40 for regulating a slide region in the direction of the base end of thesecond sleeve 3 and a stopper 41 for preventing drop-off toward the tipside. The second sleeve 3 is slidably formed between the engagement ring40 and the stopper 41.

A first sleeve 6 is provided on the inner periphery of the openingportion 2 of the arbor body 1 in such a manner that an outer peripherythereof is formed along the inner peripheral face of the opening portion2 and can retreat toward the base body side. An inclined face 6 a, forabutment against which a stepped portion 20 a of a shank 20 of thecutter B abuts, is formed on a tip of the first sleeve 6 (a lower end inFIGS. 1 and 2), and an abutment face 6 b for abutting against the innerperipheral face portion of the ball 5 and preventing more projectioninto the tip side is formed on an outer peripheral face of the firstsleeve 6. A coiled spring 8 for pressing the first sleeve 6 toward thetip of the arbor body 1 is provided on the base end side of the firstsleeve 6. A base end of the coiled spring 8 is engaged with a convexportion (spring mount seat) 1 f formed toward an inside diameter in thevicinity of a bottom of the opening portion 2 of the arbor body 1 asshown in FIG. 1. Accordingly, the first sleeve 6 can retreat from astate shown in FIG. 2 or 4 to a state shown in FIG. 1 or 5, and a slideregion is formed therebetween.

A holding hole 9 for accommodating the ball 5 therein is formed withouter and inner peripheral portions projecting into the arbor body 1 inthe slide region of the first sleeve 6 and the second sleeve 3. In otherwords, in a state in which the shank 20 of the cutter B is not inserted,the inside and outside portions of the ball 5 which accommodated in theholding hole 9 and having a periphery held in the holding hole 9 areheld by the outer peripheral face of the first sleeve 6 and the annulargroove 3 a having a U-shaped section formed on the inner peripheral faceof the second sleeve 3 as shown in FIG. 2 or 4. On the other hand, inthe state in which the shank 20 is inserted, the outside portion of theball 5 abuts against a relatively projecting portion 3 e of the secondsleeve 3 (a portion on the tip side of the above-mentioned “annulargroove 3 a having a U-shaped section”), and the inside portion of theball 5 abuts against a concave portion 23 formed on the outer peripheralface of the shank 20 of the cutter B, and is thus held as enlarged inFIG. 5.

As shown in FIG. 1 or FIG. 5 in which a main part is enlarged, the shank20 of the cutter B has a tip portion 20 b formed with such an outsidediameter to be inserted into the opening portion 2 of the arbor A, theoutside diameter of the base end portion 20 c is reduced more than thediameter of the tip portion 20 b, and a stepped portion 21 is formedtherebetween. More specifically, the outside diameter of the base endportion 20 c is equal to the inside diameter of the first sleeve 6provided on the opening portion 2 of the arbor body 1 (accurately, isslightly smaller than the inside diameter), and the stepped portion 21is formed by an inclined face (to perform a face contact on the abutmentface 6 a) corresponding to the abutment face 6 a on the tip of the firstsleeve 6. The concave portion 23 for accommodating the ball 5 is formedadjacently to the stepped portion 21 on the tip side (lower end side asshown) of the stepped portion 21. The concave portion 23 is conical.And, in the arrangement of the shank 20, the concave portion 23 isformed in three places at an interval of 120 degrees in an axiallycircumferential direction corresponding to the arrangement of the ball 5shown in FIG. 3 illustrating the axial section of the arbor A. However,the interval is not restricted to 120 degrees but may be set to an angleof, for example, 90 degrees, 60 degrees or the like. Alternatively, theangle may be non-point symmetrical with respect to an axial core. Such astructure is suitable for the case where the position of the cutter inthe direction of rotation is to be specified against the arbor. Anoutside diameter of the shank 20 between the stepped portion 21 and theconcave portion 23 is equal to the outside diameter of the tip potionwhere the first sleeve 6 on the arbor A side starts to come in contactwith the ball 5. When the shank 20 is to be inserted into the openingportion 2 of the arbor body 1, the ball 5 can smoothly be transferredfrom the outer peripheral face of the first sleeve 6 to the shank 20side. The tip side (cutting edge portion 22 side) of the concave portion23 has a diameter slightly greater than on the base end side. Thus, theball 5 is not moved toward the tip side of the shank any longer. Inother words, the portion having the larger diameter serves to functionas a stopper of the ball 5 toward the tip side.

Furthermore, a bottomed hole 10 having a smaller diameter than thediameter of the opening portion 2 of the arbor body 1 is formed on aline extending toward the base end (an upper end in FIGS. 1 and 2) sideof a center line of the opening portion 2. A compressible coiled spring11 is provided in the bottomed hole 10. On the other hand, a throughhole 25 is formed on a center line (axial core) of the shank 20 of thecutter B, and a center pin 30 is provided in the through hole (a“inserting hole” according to claim 5) 25 to freely retreat toward thearbor A side. The through hole 25 is constituted such that a base end(upper end) portion has a large diameter and the tip (lower end) sidehas an inside diameter (accurately, which is slightly larger than) equalto the outside diameter of the center pin 30, and a connecting portionthereof is provided with a tapered sheet face (a “engagement face”according to claim 5) 25 a forming a liquid sealing mechanism togetherwith the sheet face 30 a. The center pin 30 has a flange portion 30A. Alower end of the flange portion 30A is provided with a tapered sheetface 30 a which can closely come in contact with the sheet face 25 a.The lower end of the coiled spring 11 for pressing the center pin 30toward the tip is engaged with an upper end of the flange portion 30A.The center pin 30 is provided to retreat toward the arbor A side withrespect to the cutter B against the press force of the coiled spring 11.

Moreover, a helical groove 30 c is formed on the outer periphery of thecenter pin 30 excluding a predetermined dimension (distance) L from theupper end as shown in FIG. 6 illustrating the enlarged center pin. In astate in which the sheet faces 25 a and 30 a are separated from eachother, a coolant can be supplied in a necessary amount from an upperportion to a lower portion when the center pin 30 retreats to the baseend side by the predetermined dimension L or more. The predetermineddimension L is set almost equal to a dimension W at which the tip of thecenter pin 30 projects from the cutting edge portion of the tip of theshank toward the tip side in a free state (external force does not acton the center pin 30 from the tip side) in which the center pin 30 ispressed from the base end side toward the tip side by means of thecoiled spring 11.

Furthermore, a ring-shaped member 15 is provided in a slightly lowerportion of the center of the arbor body 1 in an axial direction tofreely rotate with respect to the arbor body 1 and to be liquid-tight byan O ring 16. In addition, a through hole 15 a is formed on thering-shaped member 15 toward the central side in a radial direction, anda through hole 13 is formed to communicate with the through hole 15 a.The through hole 13 has a tip which reaches the inner peripheral face ofthe bottomed hole 10 from the outer peripheral face of the arbor body 1and is opened on the inner peripheral face of the bottomed hole 10. InFIG. 1, a screw 17 fixed to the left end of the ring-shaped member 15 isto be attached to a fixture which is not shown.

Accordingly, when the coolant is supplied from the through hole 15 a ofthe ring-shaped member 15, it can be fed toward the through hole 25(center pin 30) side through the through hole 13 and bottomed hole 10 ofthe rotating arbor body 1. More specifically, a passage for the coolantis formed from the through hole 15 a of the ring-shaped member 15 to thethrough hole 25 (center pin 30). The coolant can be supplied from theinner peripheral side of the cutter B to a cut portion only duringdrilling.

In the shank attaching structure having the above-mentioned structure,the cutter can easily be attached and detached to and from the arbor inthe following manner, and a work can simply be performed without using aspecial machine tool. Furthermore, assembly can easily be carried out.In addition, the coolant can automatically be supplied to the rotatingcutter also during the drilling work if necessary. More specifically,when the cutter B is to be attached to the arbor A, the shank 20 of thecutter B is inserted into the opening portion 2 of the arbor A so thatthe stepped portion 21 of the shank 20 abuts against the inclined face 6a of the first sleeve 6, thereby causing the first sleeve 6 to retreatto the base end side of the arbor A. As a result, the constraint of theball 5 toward the inside diameter in the radial direction is released sothat the ball 5 projects into the inside diameter side. Consequently,the ball 5 is moved along the outer peripheral face of the shank 20according to the insertion of the shank 20 and is then accommodated inthe concave portion 23 of the shank 20. As a result, the shank 20 isfixed onto the arbor A side in that state as shown in FIG. 1.

When the cutter B is to be detached from the arbor A, it is sufficientthat the second sleeve 3 is moved toward the tip (downward in FIG. 1)with respect to the arbor body 1 against the elastic force of the coiledspring 4 in the state shown in FIG. 1. If the second sleeve 3 is thusmoved, the ball 5 corresponds to the annular groove 3 a of the secondsleeve 3 to move (retreat) toward the outside diameter so that a part ofthe ball 5 is accommodated in the groove 3 a. As a result, theengagement state of the ball 5 with the concave portion 23 is released.Thus, the cutter B can easily be detached downward from the arbor A. Inthis case, the first sleeve 6 is moved toward the tip side (downward inFIG. 1) with respect to the arbor body 1 by the spring force of thecoiled spring 8 according to the movement of the shank 20 downward(toward the tip side). Consequently, the ball 5 is held on the insidediameter side by the first sleeve 6 as shown in FIG. 4. In this case,the abutment face 6 b of the first sleeve 6 abuts against and holds theball 5 on the base end (upper end in FIG. 1) side. As a result, the ball5 is held in the holding hole 9 in that state.

As described above, when drilling is to be performed on a substance tobe drilled such as a steel plate with the cutter B attached to the arborA, a hose for supplying the coolant is connected to the through hole 15a of the ring-shaped member 15 shown in FIG. 1, thereby supplying thecoolant. Consequently, before the tip of the center pin 30 abuts againstthe substance to be drilled, the coolant is not supplied by the contactof the sheet faces 25 a and 30 a. When the center pin 30 retreats towardthe base end side by a predetermined dimension (the above-mentioneddimension L), that is, the drilling work is started by a cutting edgeportion 22, the coolant is supplied from the through hole 15 a to thecutting edge portion 22 of the cutter B positioned in an outsidediameter direction through the bottomed hole 10, the through hole 25 ofthe shank 20, the sheet faces 25 a and 30 a, and the spiral groove 30 cof the center pin 30.

With the shank attaching structure, since the first sleeve 6 and thesecond sleeve 3 are circular or are formed on a shape basis bycombination thereof, they can easily be processed by simply using ageneral-purpose lathe or the like. In addition, since the portions ofthe arbor body 1 are also circular or are formed on a shape basis bycombination thereof, they can easily be processed by using ageneral-purpose lathe or a drilling machine. Moreover, since the coiledspring which is an elastic member is simply attached to an innerperipheral face or an outer peripheral face, assembly can easily beperformed.

Second Embodiment

A second embodiment of the present invention will be described belowwith reference to FIGS. 7 to 11. A shank attaching structure accordingto the second embodiment is basically identical to the shank attachingstructure according to the first embodiment.

As shown in FIGS. 7 to 10, the shank attaching structure has an arbor A.The arbor A comprises an arbor body 101 including a tapered attachmentportion 112 to be attached to a rotary shaft of a driving device, abottomed hole 110 formed inside and an opening portion 102. In thevicinity of an open end of the opening portion 102, the arbor body 101comprises six holding holes 109 which penetrate a wall portion of thearbor body 101. The six holding holes 109 are provided at regularintervals around the arbor body 101. An engagement member formed by aball 105 is held in the holding holes 109.

A first sleeve 106 (which is also referred to as an inner sleeve in thepresent embodiment) is provided to freely slide over the innerperipheral face of the bottomed hole 110 of the arbor body 101 in alongitudinal direction in the vicinity of the end of the opening portion102. The first sleeve 106 is elastically pressed toward the end side ofthe opening portion 102 by a coiled spring 108. The first sleeve 106 hasa wall face 126. The wall face 126 prevents the ball 105 acting as theengagement member from projecting from the holding hole 109 into theinner peripheral side of the arbor body 101. The second sleeve 103(which is also referred to as a release collar in the presentembodiment) is provided to freely slide along the outer peripheral faceof the arbor body 101 in a longitudinal direction in the vicinity of theend of the opening portion 102. The second sleeve 103 is constituted tobe slidable in a region from a position (non-holding position) where ashank 120 of a cutter B (see FIG. 8) is not held as shown in FIG. 7 to aposition (holding position) where the shank i20 of the cutter B is heldas shown in FIG. 8. In the non-holding position, the ball 105 acting asthe engagement member is permitted to enter an annular L-shaped groove103 a which is formed on the inner peripheral face of the second sleeve103. In the non-holding position, the first sleeve 106 can be moved tohold the ball 105 acting as the engagement member on the innerperiphery.

In the holding position, the ball 105 acting as the engagement member ispushed out from the groove 103 a formed on the second sleeve 103inwardly in the radial direction and is then moved inwardly in theradial direction of the arbor body 101 as shown in FIG. 8. The ball 105cannot be moved inwardly in the radial direction of the arbor body 101as described above before the first sleeve 106 is moved toward the baseend of the arbor body 101 in the longitudinal direction. The secondsleeve 103 is pressed by a coiled spring 104 in such a direction as tomove to the holding position. The opening end side of the openingportion 102 of the coiled spring 104 is held by a stopper (springretainer) 141 for preventing drop-off. An annular engagement ring 140regulates the movement of the second sleeve 103 toward the base end sidewith respect to the arbor body 101, that is, stops a slide regionprovided toward the base end side.

A ring-shaped member (coolant collar) 115 is rotatably provided withrespect to the arbor body 101 on the outer peripheral face providedslightly below the central portion of the arbor body 101, and thering-shaped member 115 is held in that position by a snap ring 140. TwoO rings 116 are provided between the arbor body 101 and the ring-shapedmember 115 to hold a liquid-tightness therein. A coolant coupling 144 isscrewed to the ring-shaped member 115 in order to supply the coolant tothe arbor body 101. The arbor body 101 has an annular groove 146 on theouter periphery thereof, and has a through hole 113 communicating withthe groove 146 to guide the coolant from the groove 146 to the inside ofthe arbor body 101. In the present embodiment, an arbor arm 150 forpreventing the rotation of the ring-shaped member 115 in use is fixed tothe ring-shaped member 115. Furthermore, a coiled spring 111 is providedon the bottomed hole 110 of the arbor body 101.

The shank attaching structure according to the present embodiment isdesigned to use an annular cutter B. The annular cutter B is provided acenter pin 130 to freely retreat on the center line thereof. The annularcutter B includes a shank 120 having a first portion 160, a secondportion 162 and an annular projection 164 positioned in the middle ofthe first portion 160 and the second portion 162. The first portion 160and the second portion 162 have cylindrical shapes, and the firstportion 160 has a greater diameter than the diameter of the secondportion 162. The first portion 160 has a conical concave portion 123formed thereon. The conical concave portion 123 is provided at a regularinterval on the outer periphery of the shank 120. The center pin 130 hasa flange portion 130A for closely coming (seating) in contact with theinside of the arbor body 101, and a longitudinal (axial) groove 130 c(see FIGS. 9 to 11) capable of supplying the coolant to the cutter Bside.

In use, the shank attaching structure having the above-mentionedstructure is designed such that a shank portion of the cutter B can beinserted into the opening portion 102 of the arbor body 101 and thecutter B can surely be held in the arbor body 101 when the insertion iscompleted. The shank attaching structure is set in a state shown in FIG.7 at the beginning. When the cutter B is inserted into the openingportion 102 of the arbor body 101, the annular projection 164 is engagedwith the first sleeve 106. Consequently, the first sleeve 106 is movedtoward the base end side of the arbor body 101 against the press forceof the coiled spring 108. As soon as the cutter B is completely insertedinto the arbor body 101, the ball 105 acting as the engagement member ismoved inwardly in the radial direction and is then engaged with theconcave portion 123 of the shank 120 of the cutter B. This operation isautomatically performed through the second sleeve 103 by the press forceof the coiled spring 104. At the same time that the operation of theball 105 into the concave portion 123 is performed, the second sleeve103 is moved to the holding position (see FIG. 8) by the press force ofthe coiled spring 104. The coolant can be supplied into the arbor body101 through the ring-shaped member 115. During a cutting work, thecutter B is cut into a substance to be cut. Therefore, the center pin130 is pressed toward the base end side with respect to the arbor body101, and the flange portion 130A of the center pin 130 is released froma state in which it is in close contact with the inside of the cutter B.As shown in FIGS. 9 to 11, this operation permits the coolant to besupplied to the groove 130 c through the flange portion 130A of thecenter pin 130. An O ring 117 provided in the arbor body 101 functionsas a seal between the arbor body 101 and the shank 120 of the cutter B.Consequently, it is possible to prevent the coolant from leaking out tothe outer periphery of the cutter B.

The cutter B attached to the arbor A is detached by moving the secondsleeve 103 by hands toward the tip side of the arbor body 101 againstthe press force of the coiled spring 104. In the state of thenon-holding position (see FIG. 7), the ball 105 is automatically movedoutwardly in the radial direction by the function of the press force ofthe coiled spring 108 through the first sleeve 106 or through the shank120 of the cutter B. When the ball 105 is moved outwardly in the radialdirection, the cutter B is automatically discharged from the arbor body101 by the press force of the coiled spring 111 through the first sleeve106. At the same time that the cutter B is discharged, the first sleeve106 is automatically moved toward the tip side of the arbor body 101 upto a position where an abutment face 106 b abuts against the ball 105.In the state in which the first sleeve 106 is moved toward the tip side,it prevents the glove 105 from projecting into inner-side of the arborbody 101.

Industrial Applicability

The shank attaching structure according to the present invention can beutilized for attaching and detaching a cutting tool such as a cutter toand from a drilling machine, a hand powered drill, a hammer drill andthe like. In addition, the shank attaching structure is simplified, iseasy to work and can easily be assembled in a short time.

Accordingly, it is possible to manufacture the shank attaching structuremore inexpensively than a conventional shank attaching structure and toobtain high reliability with the simple structure.

Moreover, the attachment and detachment of a cutter to the arbor sidecan easily be performed by one hand. Therefore, it is possible to save atime taken to exchange tools and to relieve an operator's labor.

Furthermore, it is possible to implement a one-touch typed shankattaching structure in which a coolant can be supplied easily andeffectively only during a work.

What is claimed is:
 1. A shank attaching structure in which anengagement member is provided on an inner peripheral face of an openingportion formed on a tip of an arbor so as to freely retreat in adirection of an outside diameter, and a shank provided on a base end ofa cutter is detachably attached to the opening portion of the arbor withone touch, wherein the shank is formed to have such an outside diameteras to pass in a state in which the engagement member provided on thearbor retreats in the direction of the outside diameter, a diameter of abase end portion of the shank is further reduced to form a steppedportion for abutment, and a concave portion(s) for accommodating aprojected portion of the engagement member projected in a direction ofan inside diameter is/are formed on a tip side portion of the steppedportion, a first sleeve is provided on the inner peripheral face of theopening portion of the arbor in such a manner that a tip of the firstsleeve can abut against the stepped portion of the shank to retreattoward a base end side and the state in which the engagement member iscaused to retreat in the direction of the outside diameter can be keptby an outer peripheral face of the first sleeve, a holding hole forholding the engagement member in a slide operation region of the firstsleeve is formed in a wall portion of the arbor, the state in which theengagement member retreats in the direction of the outside diameter iskept until a tip of the first sleeve pressed toward an open end by anelastic member to be abut by the stepped portion of the shank, a secondsleeve is provided on the outer peripheral face of the arbor for beingmoved in at least one of directions of an axial tip and a base end,pressing the engagement member in the direction of the inside diameterby the inner peripheral face of the second sleeve with the movement inone of the directions, and accommodating the engagement member in thedirection of the outside diameter without the movement in one of thedirections, and the second sleeve is pressed in one of the directions byan elastic member, thereby keeping a state in which the engagementmember is accommodated in the concave portion of the shank, and thesecond sleeve is moved in a direction opposite to the one of thedirections against elastic force of the elastic member, thereby causingthe engagement member to retreat in the direction of the outsidediameter.
 2. The shank attaching structure according to claim 1, whereinone of the axial directions of the second sleeve is a base end side anda direction opposite to the one of the axial directions is a tip side.3. The shank attaching structure according to claim 1, wherein one ofthe axial directions of the second sleeve is a tip side and a directionopposite to the one of the axial directions is a base end side.
 4. Theshank attaching structure according to claim 1, wherein the engagementmember is a ball, the elastic member for pressing the first sleeve isformed of a coiled spring having such a dimension as to cause the outerperiphery of the coiled spring to be provided along the inner peripheralface of the opening portion of the arbor, and the elastic member forpressing the second sleeve is a coiled spring having such a dimension asto cause the inner periphery of the coiled spring to be provided alongthe outer peripheral face of the arbor and to cause the outer peripheryof the coiled spring to be provided along the inner peripheral face ofthe second sleeve.
 5. The shank attaching structure according to claim1, wherein the opening portion of the arbor is extended toward the baseend side to form a hole portion for supplying a coolant and to form, onthe hole portion, a through hole having a tip open and extending in aradial direction is formed on the hole portion, a ring member isrotatably attached to the arbor on the outer periphery of the arborwhere the hole is positioned, and a sealing member for a liquid seal isprovided between the ring member and the arbor, and a passage forsupplying the coolant from an upper end toward a tip side is formed inan axial core portion of the shank.
 6. The shank attaching structureaccording to claim 4, wherein the opening portion of the arbor isextended toward the base end side to form a hole portion for supplying acoolant and to form, on the hole portion, a through hole having a tipopen and extending in a radial direction is formed on the hole portion,a ring member is rotatably attached to the arbor on the outer peripheryof the arbor where the hole is positioned, and a sealing member for aliquid seal is provided between the ring member and the arbor, and apassage for supplying the coolant from an upper end toward a tip side isformed in an axial core portion of the shank.
 7. The shank attachingstructure according to claim 5, wherein a coiled spring is provided inthe hole portion for supplying the coolant, and a center pin is providedin a inserting hole of the shank so as to retreat toward the holeportion side in such a manner that it is pressed toward a tip side bythe coiled spring and the tip projects from a tip of a cutter, and aflange portion is formed in a base end portion of the center pin forbeing engaged with the shank side when the center pin projects, and aliquid sealing mechanism is formed for performing a liquid seal in astate in which the flange portion abuts against an engagement face of anupper end of the inserting hole with which the flange portion isengaged.
 8. The shank attaching structure according to claim 6, whereina coiled spring is provided in the hole portion for supplying thecoolant, and a center pin is provided in a inserting hole of the shankso as to retreat toward the hole portion side in such a manner that itis pressed toward a tip side by the coiled spring and the tip projectsfrom a tip of a cutter, and a flange portion is formed in a base endportion of the center pin for being engaged with the shank side when thecenter pin projects, and a liquid sealing mechanism is formed forperforming a liquid seal in a state in which the flange portion abutsagainst an engagement face of an upper end of the inserting hole withwhich the flange portion is engaged.
 9. The shank attaching structureaccording to claim 7, wherein the flange portion and the engagement faceforming the liquid sealing mechanism comprise tapered faces which arecontacted each other.
 10. The shank attaching structure according toclaim 8, wherein the flange portion and the engagement face forming theliquid sealing mechanism comprise tapered faces which are contacted eachother.
 11. The shank attaching structure according to claim 9, wherein agroove for forming a coolant passage is provided below a position whichis lower by a predetermined dimension based on a lower portion of theflange portion of the center pin in the composition which includes theouter peripheral face of the center pin and the inner peripheral face ofthe inserting hole of the shank which is in contact with the outerperipheral face.
 12. The shank attaching structure according to claim10, wherein a groove for forming a coolant passage is provided below aposition which is lower by a predetermined dimension based on a lowerportion of the flange portion of the center pin in the composition whichincludes the outer peripheral face of the center pin and the innerperipheral face of the inserting hole of the shank which is in contactwith the outer peripheral face.
 13. The shank attaching structureaccording to claim 11, wherein the position which is lower by thepredetermined dimension is substantially equal to a dimension with whichthe center pin projects from a cutting edge portion on the tip of thecutter toward the tip side in a free state in which the center pin ispressed from the base end toward the tip by the coiled spring.
 14. Theshank attaching structure according to claim 12, wherein the positionwhich is lower by the predetermined dimension is substantially equal toa dimension with which the center pin projects from a cutting edgeportion on the tip of the cutter toward the tip side in a free state inwhich the center pin is pressed from the base end toward the tip by thecoiled spring.